//https://leetcode.cn/problems/sqrtx/

class Solution {
public:
    int mySqrt(int x) {
        if (x < 1)
            return 0;

        long long left = 0, right = x;
        long long mid = 0;
        while (left < right)
        {
            mid = left + (right - left + 1) / 2;
            if (mid * mid <= x)
                left = mid;
            else
                right = mid - 1;
        }

        return left;

    }
};